class Todo(object):
    current_todo_id = 1
    @classmethod
    def next_id(cls):
        todo_id = Todo.current_todo_id
        Todo.current_todo_id += 1
    def __init__(self,title:str,id:int=0,completed=False):
        self.id = id
        self.title = title
        self.completed = completed
    def add_obj(self,title):
        return Todo(title)
a=Todo('aa')
print(a.__dict__)
